As pointed out in the previous application, one of the great advances in medical technology in recent years is the development of automated equipment for performing comprehensive analyses of blood samples, to give readings of factors identified as red cell count, white cell count, hemoglobin, hematocrit, mean cell volume, mean cell hemoglobin, and mean cell hemoglobin concentration. An automated hematology analyzer aspirates a specimen of blood from a sample container, performs the required tests, prints out the test results, and prepares the equipment for the next specimen, in a time interval less than one minute.
Samples of patients' blood are provided in standard sample containers having rubber stopper closures. Specimen input to the analyzer is both "open" and manual, that is, a technician must take a previously shaken sample container (or must shake the container a predetermined amount), open the container by removing the stopper, immerse the aspirator tip of the analyzer into the sample, and actuate the analyzer. After the specimen input has been completed, the container must be restoppered and disposed of, and any liquid adhering to the outside of the aspirator tip must be removed.
Because the sample container must be opened and manually introduced into the system, laboratory personnel is exposed to a potentially dangerous environment.
All laboratory specimens are regarded as hazardous. Pathogenic microorganisms are readily spread to laboratory personnel by direct contact. With blood samples there is particular concern over exposure to serum hepatitis. The open input of blood specimens to automated systems as described above results in exposure of technicians to contact with the blood dripping from the aspirator tip of the equipment, as well as the residual blood in the container and on the rubber stopper.
My copending application referred to above covers an arrangement for a "closed" specimen input to the analyzer, by enabling transfer of blood from a closed container to the analyzer without exposing the technician to contact with the blood before or after aspiration. The unopened container is secured in a suitable holder: when a manual control is operated a compound transfer needle, connected by an aspiration tube to the analyzer, is forced to enter the container by penetrating the stopper. After aspiration of the sample, the needle is raised out of the container, the stopper material acting to wipe away any liquid adhering to the external surface of the needle, and then to reseal the container. The result is an improved method in which the technician is never exposed to contact with blood at any time.
Refinements in the field of hematology analyzers have resulted in the opportunity for improving the structure described in the previous application. Sources of positive and negative fluid pressure are now available: the analyzer also now includes an automatic procedure for rinsing a sampling needle after each sample is taken, so provision must be made for suitably disposing of the rinsing fluid.